/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.crazymaker.servlet.container.netty.resource;

import lombok.extern.slf4j.Slf4j;

import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.attribute.BasicFileAttributes;
import java.security.cert.Certificate;
import java.util.jar.Manifest;

/**
 * Represents a single resource (file or directory) that is located on a file
 * system.
 */
@Slf4j
public class FileResource extends AbstractResource
{


    private static final boolean PROPERTIES_NEED_CONVERT;

    static
    {
        boolean isEBCDIC = false;
        try
        {
            String encoding = System.getProperty("file.encoding");
            if (encoding.indexOf("EBCDIC") != -1)
            {
                isEBCDIC = true;
            }
        } catch (SecurityException e)
        {
            // Ignore
        }
        PROPERTIES_NEED_CONVERT = isEBCDIC;
    }


    private final File resource;
    private final String name;
    private final boolean readOnly;
    private final Manifest manifest;
    private final boolean needConvert;

    public FileResource(WebResourceRoot root, String webAppPath,
                        File resource, boolean readOnly, Manifest manifest)
    {
        super(root, webAppPath);
        this.resource = resource;

        if (webAppPath.charAt(webAppPath.length() - 1) == '/')
        {
            String realName = resource.getName() + '/';
            if (webAppPath.endsWith(realName))
            {
                name = resource.getName();
            } else
            {
                // This is the root directory of a mounted ResourceSet
                // Need to return the mounted name, not the real name
                int endOfName = webAppPath.length() - 1;
                name = webAppPath.substring(
                        webAppPath.lastIndexOf('/', endOfName - 1) + 1,
                        endOfName);
            }
        } else
        {
            // Must be a file
            name = resource.getName();
        }

        this.readOnly = readOnly;
        this.manifest = manifest;
        this.needConvert = PROPERTIES_NEED_CONVERT && name.endsWith(".properties");
    }

    @Override
    public long getLastModified()
    {
        return resource.lastModified();
    }

    @Override
    public boolean exists()
    {
        return resource.exists();
    }

    @Override
    public boolean isVirtual()
    {
        return false;
    }

    @Override
    public boolean isDirectory()
    {
        return resource.isDirectory();
    }

    @Override
    public boolean isFile()
    {
        return resource.isFile();
    }

    @Override
    public boolean delete()
    {
        if (readOnly)
        {
            return false;
        }
        return resource.delete();
    }

    @Override
    public String getName()
    {
        return name;
    }

    @Override
    public long getContentLength()
    {
        return getContentLengthInternal(needConvert);
    }

    private long getContentLengthInternal(boolean convert)
    {
        if (convert)
        {
            byte[] content = getContent();
            if (content == null)
            {
                return -1;
            } else
            {
                return content.length;
            }
        }

        if (isDirectory())
        {
            return -1;
        }

        return resource.length();
    }

    @Override
    public String getCanonicalPath()
    {
        try
        {
            return resource.getCanonicalPath();
        } catch (IOException ioe)
        {
            if (log.isDebugEnabled())
            {
                log.debug("fileResource.getCanonicalPathFail：" + resource.getPath(), ioe);
            }
            return null;
        }
    }

    @Override
    public boolean canRead()
    {
        return resource.canRead();
    }

    @Override
    protected InputStream doGetInputStream()
    {
        if (needConvert)
        {
            byte[] content = getContent();
            if (content == null)
            {
                return null;
            } else
            {
                return new ByteArrayInputStream(content);
            }
        }
        try
        {
            return new FileInputStream(resource);
        } catch (FileNotFoundException fnfe)
        {
            // Race condition (file has been deleted) - not an error
            return null;
        }
    }

    @Override
    public final byte[] getContent()
    {
        // Use internal version to avoid loop when needConvert is true
        long len = getContentLengthInternal(false);

        if (len > Integer.MAX_VALUE)
        {
            // Can't create an array that big
            throw new ArrayIndexOutOfBoundsException(
                    "abstractResource.getContentTooLarge" + getWebappPath());
        }

        if (len < 0)
        {
            // Content is not applicable here (e.g. is a directory)
            return null;
        }

        int size = (int) len;
        byte[] result = new byte[size];

        int pos = 0;
        try (InputStream is = new FileInputStream(resource))
        {
            while (pos < size)
            {
                int n = is.read(result, pos, size - pos);
                if (n < 0)
                {
                    break;
                }
                pos += n;
            }
        } catch (IOException ioe)
        {
            if (log.isDebugEnabled())
            {
                log.debug("abstractResource.getContentFail" +
                        getWebappPath(), ioe);
            }
            return null;
        }

        if (needConvert)
        {
            // Workaround for certain files on platforms that use
            // EBCDIC encoding, when they are read through FileInputStream.
            // See commit message of rev.303915 for original details
            // https://svn.apache.org/viewvc?view=revision&revision=303915
            String str = new String(result);
            try
            {
                result = str.getBytes(StandardCharsets.UTF_8);
            } catch (Exception e)
            {
                result = null;
            }
        }
        return result;
    }


    @Override
    public long getCreation()
    {
        try
        {
            BasicFileAttributes attrs = Files.readAttributes(resource.toPath(),
                    BasicFileAttributes.class);
            return attrs.creationTime().toMillis();
        } catch (IOException e)
        {
            if (log.isDebugEnabled())
            {
                log.debug("fileResource.getCreationFail" +
                        resource.getPath(), e);
            }
            return 0;
        }
    }

    @Override
    public URL getURL()
    {
        if (resource.exists())
        {
            try
            {
                return resource.toURI().toURL();
            } catch (MalformedURLException e)
            {
                if (log.isDebugEnabled())
                {
                    log.debug("fileResource.getUrlFail" + resource.getPath(), e);
                }
                return null;
            }
        } else
        {
            return null;
        }
    }

    @Override
    public URL getCodeBase()
    {
        if (getWebappPath().startsWith("/WEB-INF/classes/") && name.endsWith(".class"))
        {
            return getWebResourceRoot().getResource("/WEB-INF/classes/").getURL();
        } else
        {
            return getURL();
        }
    }

    @Override
    public Certificate[] getCertificates()
    {
        return null;
    }

    @Override
    public Manifest getManifest()
    {
        return manifest;
    }

}
